Alvin related his conversation with Paulina to Harold, and all Paulina had told him about her kind and meek mistress.
After listening to Alvin's disappointing response, he concluded that he should have questioned the maid by himself. If you wanted a job like that done well, then you had to do it yourself. Not that he didn't trust Alvin to get his job done, but Alvin didn't have enough information, so he didn't exactly know what to ask, hence he didn't get the answers that he wanted.
Although he trusted Alvin, he had yet to tell Alvin about Alicia being an exiled princess or about meeting her in the woods, so he believed Paulina had tried to hide it from him and told him nothing about it.